# std::filesystem::exists

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< cpp‎ | filesystem

Defined in header `<filesystem>` |  |
bool exists( std::filesystem::file_status s ) noexcept; | (1) | (since C++17)
bool exists( const std::filesystem::path& p ); | (2) | (since C++17)
bool exists( const std::filesystem::path& p, std::error_code& ec ) noexcept; | (3) | (since C++17)

Checks if the given file status or path corresponds to an existing file or directory.

1) Equivalent to status_known(s) && s.type() != file_type::not_found.
2,3) Let s be a std::filesystem::file_status determined as if by status(p) or status(p, ec) (symlinks are followed), respectively. Returns exists(s). The non-throwing overload calls ec.clear() if status_known(s).

### Parameters

s | - | file status to check
p | - | path to examine
ec | - | out-parameter for error reporting in the non-throwing overload

### Return value

true if the given path or file status corresponds to an existing file or directory, false otherwise.

### Exceptions

Any overload not marked `noexcept` may throw std::bad_alloc if memory allocation fails.

2) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument.
3) Sets a std::error_code& parameter to the OS API error code if an OS API call fails, and executes ec.`clear`() if no errors occur.

No filesystem exception is thrown if object does not exist (use return value).

### Notes

The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling exists(*iterator) is less efficient than exists(iterator->status()).

### Example

Run this code

    #include <cstdint>
    #include <filesystem>
    #include <fstream>
    #include <iostream>
    namespace fs = std::filesystem;

    void demo_exists(const fs::path& p, fs::file_status s = fs::file_status{})
    {
        std::cout << p;
        if (fs::status_known(s) ? fs::exists(s) : fs::exists(p))
            std::cout << " exists\n";
        else
            std::cout << " does not exist\n";
    }

    int main()
    {
        const fs::path sandbox{"sandbox"};
        fs::create_directory(sandbox);
        std::ofstream{sandbox/"file"}; // create regular file
        fs::create_symlink("non-existing", sandbox/"symlink");

        demo_exists(sandbox);

        for (const auto& entry : fs::directory_iterator(sandbox))
            demo_exists(entry, entry.status()); // use cached status from directory entry

        fs::remove_all(sandbox);
    }

Output:

    "sandbox" exists
    "sandbox/symlink" does not exist
    "sandbox/file" exists

### See also

statussymlink_status (C++17)(C++17) | determines file attributes determines file attributes, checking the symlink target (function)
file_status (C++17) | represents file type and permissions (class)
exists | checks whether directory entry refers to existing file system object (public member function of `std::filesystem::directory_entry`)

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